Transport of electrons in compressed Li, Na, and K: Thermoelectric powers, resistivities, and Hall coefficients

The diffusion-thermoelectric power coefficients, resistivities, and Hall coefficients of Li, Na, and K are computed for high temperatures as functions of pressure using a relaxation-time approximation solution to the Boltzmann equation. The electron-phonon interaction is treated in a rigid-ion model, the electrons are assumed free, and the ion structure factor is constructed from pressure-dependent elastic-constant data. Account is taken of anisotropic scattering, nonlocal-pseudopotential effects, and the "kinetic-anisotropy" effect, all of which are important. The agreement between theory and experiment is generally very good, the small discrepancies between theoretical and experimental values of the transport coefficients being directly ascribable to uncertainties in the pseudopotentials and structure factors employed. Surprisingly, the thermoelectric powers and their pressure dependences are less sensitive to details of the pseudopotentials than the resistivities. These calculations suggest that large thermoelectric-power coefficients are associated with anisotropic (as well as energy-dependent) scattering, and with pseudopotentials $V\left(q\right)\mathrm{}$ such that the product of $\mathrm{}\left|V\right(q\left)\right|$ and $\frac{\partial \mathrm{}\left|V\right|\mathrm{}}{\partial q}$ is large for $q$ near $2k_F$.